Low Cost 27 MHz 3.3 Volt VCXO

The IDT728 combines the functions of a VCXO (Voltage Controlled Crystal Oscillator) and PLL (Phase Locked Loop) frequency doubler onto a single chip. Used in conjunction with an external pullable quartz crystal, this monolithic integrated circuit replaces more costly hybrid (canned) VCXO devices. The IDT728 is designed primarily for data and clock recovery applications within end products such as set-top box receivers. The IDT728 exhibits a moderate VCXO gain of 110 ppm/V typical, when used with a high quality external pullable quartz crystal. The frequency of the on-chip VCXO is adjusted by an external control voltage input into pin VIN. Because VIN is a high impedance input, it can be driven directly from an PWM RC integrator circuit. Frequency output increases with VIN voltage input. The usable range of VIN is 0 to 3.3 V.